Oracle 函数 实现简单的加密解密

Oracle 函数 实现简单的加密解密

1. 加密算法 create or replace function encrypt (in_string varchar2,shift number) return varchar2 is
    lv_out_string varchar2(100);
    lv_in_string varchar2(100);
    lv_length number(5);
    lv_count number(5);
    lv_temp varchar2(1);
    lv_shift number(5);
begin
    lv_shift := mod(shift,26);
    lv_in_string := lower(in_string);
    select LENGTH(lv_in_string),1,'' into lv_length,lv_count,lv_out_string from dual;
    
    for lv_count in    1.. lv_length loop
                             lv_temp := substr(lv_in_string,lv_count,1);
                             if ascii(lv_temp) <97    or ascii(lv_temp) >122 then
                                    lv_out_string := lv_out_string || lv_temp;
                             else
                                    if ascii(lv_temp)+lv_shift>122 then
                                         lv_temp :=chr(ascii(lv_temp)+lv_shift - 26);
                                    else
                                         lv_temp := chr(ascii(lv_temp)+lv_shift);
                                    end if;
                                     lv_out_string := lv_out_string || lv_temp;
                             end if;
    end loop;
    return lv_out_string;
end encrypt ;       2. 解密算法   create or replace function decrypt (in_string varchar2,shift number) return varchar2
is
lv_out_string varchar2(10);
lv_length number(3);
lv_count number(3);
lv_temp    varchar2(100);
lv_shift number(3);

begin
                 lv_shift := mod(shift,26);
                 select length(in_string),1,'' into lv_length, lv_count,lv_out_string from dual;
                 for lv_count    in 1.. lv_length loop
                         lv_temp :=substr(in_string,lv_count,1);
                         if ascii(lv_temp) <97 or ascii(lv_temp)>122 then
                                lv_out_string := lv_out_string || lv_temp;
                             else
                                    if ascii(lv_temp)-lv_shift    <97 then
                                         lv_temp := chr(ascii(lv_temp) - lv_shift +26);

                                         else
                                         lv_temp := CHR(ASCII(lv_temp) - lv_shift);
                                    end if;
                                    lv_out_string := lv_out_string || lv_temp;
                         end if;
                 end loop;
                 return    lv_out_string;
end decrypt;